We plan to study the multiple simultaneous displacement patterns of walking of patients with selected neurological skeletal or arthritis disabilities. We will attempt to characterize the displacement patterns of patients in selected disease states and to measure the changes in their walking performance after different medical and surgical treatment or with the use of various assistive devices such as canes, crutches, orthotic devices, etc. These abnormal gait patterns will be compared with standards of normal variability which we have established for men and women in various age and height groups under various conditions of walking. In addition to studying walking performance, we plan to study mechanisms which alone or in combination contribute to gain abnormalities of patients in above-mentioned disability categories. Such mechanisms include muscle weakness, joint immobility, postural unsteadiness and instability, and muscle spasticity or rigidity. BIBLIOGRAPHIC REFERENCES: Gore, D.R., Murray, M.P., Sepic, S.B. and Gardner, G.M.: Walking patterns of men with unilateral surgical hip fusion. J. Bone Joint Surg. 57-A:759-765, September l975. Murray, M.P., Guten, G.N., Baldwin, J.M. and Gardner, G.M.: A comparison of plantar flexion torque with and without the triceps surae. Acta Orthop. Scand. 47:122-124, February, l976.